1. Field of the Invention
The present invention relates to a ground contacting system for use in shoes which provide a damping action to cushion foot impact, a 3D force reduction action to reduce force transference and a deflecting action to allow a slight, but detectable displacement of user""s foot relative to the ground contacting system.
More particularly, the present invention relates to a ground contacting system including a first plurality of 3D deformable, deflectable, damping elements projecting downward from an undersurface of an outsole and/or a second plurality of 3D deformable, deflectable, damping elements having a portion projecting downward from the outsole undersurface and having a second portion wrapping up above the undersurface of the outsole onto an upper where the elements cushion foot impact, reduce force transference three dimensionally and allow for a slight, but measurable displacement of the user""s foot relative to a ground contacting surface of the elements in the direction of the forces associated with foot fall.
2. Description of Related Art
Footwear intended for physical activity includes an upper and a securely attached sole. The upper wraps around some or all of a wearer""s foot, and is typically held in place by shoelaces. Soles typically include an inner sole, a midsole, and an outsole. Midsoles are generally formed of a cushioning material while outsoles are wear-resistant layers. Overall, soles are designed to provide stability and absorb impact loading caused by the foot of a wearer coming down upon the ground.
Significant engineering goes into providing and balancing design parameters for stability and cushioning. Special EVA foam materials have been formulated for use in midsoles. Various manufacturers have incorporated devices in the midsole to provide stability, cushioning, or, hopefully, both. For example, one major footwear manufacturer incorporates an air bag that is filled with a high molecular weight gas in order to provide substantial cushioning underneath the heal of the wearer. That manufacturer also provides midsole structure to enhance sole stability that is lost due to the presence of the air bag. Another manufacturer has used a gel-filled bag in the midsole to absorb impact. Another manufacturer provides xe2x80x9ccantileverxe2x80x9d technology to provide cushioning with a goal toward a minimum loss of stability.
Examples of devices designed to provide stability include heel counters, variable density EVA foams in the midsole, and inelastic straps going from the fore foot to the heel section of the shoe.
It is common knowledge in the footwear industry that a runner will experience less leg fatigue and muscle and joint stress by running on a dirt road than on a paved road over equal distances. Folklore has always attributed the difference to the theory that the dirt road provides a softer or more cushioned surface upon which to run. However, empirical tests have suggested that many dirt roads are just as hard as paved roads when measured under vertical impact loading. The applicants of the present invention have therefore theorized that dirt roads may provide the advantage of a small amount of sliding each time a runner""s foot contacts the ground.
When running on a dirt road, the runner""s foot will go through a forward motion until it makes initial contact with the ground whereupon it slides forward slightly until coming to a rest. This action is repeated for each step. Because impact is measured as force divided by the amount of time the force is applied, the impact on a leg is lessened by the foot""s sliding because the force of each step is applied over a greater amount of time. This is contrasted with running on pavement wherein the foot moves forward between steps and upon initial ground contact the foot comes to an immediate halt without any substantial forward sliding. Thus, the impact load on the foot, and hence the leg, is substantially greater.
Additionally, runners run with their knees bent. Thus, the lower leg forms a pivot point at the knee. During the time that the foot transitions from forward motion to a dead stop there is a rearward force (friction) on the bottom of the shoe by the ground which acts to pivot the lower leg about the knee, thus creating a moment at the knee joint. This moment must be resisted, in part, by the quadriceps and knee ligaments. It is the applicant""s theory that when a runner runs on a dirt or gravel road the small amount of forward sliding that occurs upon each footfall reduces the moment at the knee due to impact loads because the amount of time that the load is applied is increased while the magnitude of the load does not change.
Similar kinematics apply to sports other than running. When tennis is played on a clay court the players experience some sliding each time a foot plant is performed. Conversely, when tennis is played on an asphalt court players may experience greater muscle fatigue because the foot cannot slide during sudden stops thus creating greater impact.
Numerous foreign patent and applications and numerous United States patents have disclosed, taught and claimed various techniques for imparting cushioning and stability to a shoe. However, none of these techniques have simultaneously optimized the bio-mechanical characteristics of the shoe. Thus, it would represent an advancement in the art to produce soles that can be continuously woven into the upper so that there is a smooth transition from the sole element to the upper element so that the foot can be better supported and better accommodated by a shoe so constructed.
Generally, the present invention provides a ground contacting system having a damping action to cushion foot impact, a 3D deflecting action to allow a slight, but detectable displacement of a sole relative to a ground contacting surface(s) of the ground contacting system, a 3D force reduction action, and an energy dissipating action in response to an applied force. The ground contacting system of the present invention is designed to optimize various parts of the shoe so that bio-mechanical stresses and strains on a wearer can be minimized without adversely affecting shoe performance and the overall feel of the shoe to the wearer. Additionally, the ground contacting system of the present invention when applied to a sports shoe or running shoes, affords damping support and guide actions which can be tailored to be individual needs of the wearer.
In particular, the present invention provides a ground contacting system including at least one 3D deflectable/ distortable/deformable element attachably engaged to an underside of a sole where the element cushions foot impact, dissipates the energy associated with foot impact, reduces the force associated with foot impact three dimensionally, and allows for a slight, but measurable displacement of the sole relative to a ground contacting zone of the element when the element is in direct contact with a ground surface in the direction of an applied force associated with foot impact.
The present invention also provides a ground contacting system including at least one 3D deflectable/distortable/deformable element attachably engaged to an underside sole having a portion parallel to the underside of the sole and having a second portion wrapping up and extending above the sole an amount sufficient to cushion lateral and/or side foot impact, to enhance stability, to inhibit rollover, to dissipate the energy associated with foot impact, to reduce force transference three dimensionally, and to allow a slight, but measurable displacement of the sole and/or shoe relative to a ground contacting zone of the element in the direction of an applied force associated with foot impact.
The present invention also provides a ground contacting system including at least one of a first 3D deformable element attachably engaged to an underside of a sole where the first element cushions foot impact, dissipates energy, reduces three dimensional force transference, and allows for a slight, but measurable displacement of the sole relative to a ground contacting zone of the element in a plane parallel to a ground contacting zone when the element is in direct contact with a ground surface and at least one of a second 3D deformation element attachably engaged to the sole having a first portion parallel to the underside of the sole and having a second portion wrapping up and extending above the sole, an amount sufficient to cushion lateral and/or side foot impact to enhance stability, to inhibit rollover, to dissipate energy, reduces three dimensionally force transference and to allow a slight, but measurable displacement of the shoe relative to the ground contacting zone of the elements.
The present invention also provides ground contacting system elements that have greater vertical deformation than horizontal deformation and, alternatively, elements that have greater horizontal deformation than vertical deformation.
The present invention also provides soles having the ground contacting system of this invention incorporated therewith.
The present invention also provides shoes including a sole having the ground contacting system of this invention incorporated therewith.
The present invention also provides methods for three dimensional reduction of force transference and dissipating energy associated with foot impact at contact surfaces between a shoe and a ground surface. The energy dissipation involves the conversion of some of the foot fall impact to heat through distortion of a ground contacting system associated with the shoe at positions on the shoe that engage the ground surface. The ground contacting system is designed to distort three dimensionally so that the force transference associated with foot impact is reduced and some of the energy associated with ground contact is dissipated primarily in the ground contacting system.
The present invention also provides a method for reducing stress and strain on a wearer""s feet, ankles, legs and back, where the wearer""s foot can move a slight amount in the direction of foot impact relative to surfaces of ground contact and to reduce force transference of foot impact in three dimensions and dissipate the energy of foot impact which reduces joint moments such as moments in the ankle, knee, and the like. The three dimension of deformation include a vertical dimension (perpendicular to the ground contact surface) and two horizontal dimensions (in a plane substantially parallel to the ground contact surface) that form a right-handed (or left handed) orthogonal coordinate system.